Evaluating Coastal Surface Water Quality in Ben Tre Province, Vietnam

Abstract

This study was conducted to assess the quality of surface water in the coastal area of Ben Tre province in 2020. Surface water quality in the study area was evaluated based on the values of eight water quality criteria including pH, salinity, total suspended solids (TSS), dissolved oxygen (DO), ammonium (N-NH₄⁺) concentration, total open oil, iron (Fe) and coliforms. Water quality was assessed using QCVN 10-MT:2015/BTNMT National technical regulation on marine water quality. Coastal water quality was classified using cluster analysis. The results showed that TSS, coliform, and oil and grease in coastal water exceeded the allowable limits of QCVN 10-MT:2015/BTNMT. The concentration of Fe only exceeds the allowable limit in some positions while N-NH₄⁺ is asymptotically close to the allowable limit. DO, salinity, Fe, oil and grease in the dry season were significantly higher than those in the rainy season. Meanwhile, N-NH₄⁺ and Coliform were higher in the rainy season than those in the dry season. TSS of March and September was higher than that of June and November. pH has little seasonal variation. CA classified coastal water quality into three clusters due to the difference in concentrations of salinity, TSS, oil and grease, and coliform. Further studies need to add monitoring indicators such as phosphorus, organic matters (chemical oxygen demand, biological oxygen demand) and heavy metals to more comprehensively assess water quality in coastal areas for appropriate management solutions. Coastal water quality needs to be protected as it plays an important role in the local economic development.